Why are leaves green and blood red? The answer lies with one family of pigments, the porphyrins and their relatives. These pigments are also responsible for the fundamental energetic processes that make life as we know it possible. The properties of these colorful molecules are now being investigated for use in a wide range of applications, from cancer therapy to microelectronics. The Colours of Life is intended to be an introduction to the porphyrins and their role in life.